1. Field of the Invention
The invention relates to management of personal documents & data, identity information and any other information relevant to citizens. In particular, the invention relates to the management of documents and data in a secure fashion using electronic (e-) signatures and in particular to a method and apparatus for utilising biometric techniques with such signatures.
2. Description of the Related Art
It should be appreciated that as used herein, “citizen” is intended to mean any person or user, including consumers and employees, and is not intended to be limited to any political definition thereof. Moreover, the term electronic signature as used herein is intended to indicate both symmetric key based electronic signatures and asymmetric (public key) digital signatures. At present, management of personal documents such as a passport or a driving license is performed in hard copy. Performing transactions requiring such documents such as taxing a motor vehicle typically involves a complex procedure with much manual handling of documents and use of the postal system.
EP 0 917 119 describes a system for the safe, secure and properly authorized transfer of information while preserving individual privacy. It enables this by the provision of a first datastore including static identification information for a user, a second datastore including moderately dynamic personal data about a user and a third datastore including dynamic demographic information about a user. By utilising these multiple datastores it is possible to selectively access, organize and use personal data.
U.S. Pat. No. 6,105,131 discloses a secure server in a secure distributed information system that isolates interaction from terminals to specific personal vaults. A secure connection server is coupled to the system to enable authentication of a user and the data within the vault is protected against disclosure by encryption, against tampering by digital signatures and against un-trusted communications with unknown parties by digital certificates.
Although these known systems provide a level of security for access to data, the security is not based on personalised security features and is therefore open to tampering by persons of unscrupulous nature.
Electronic signatures are well known for the protection and authentication of electronic documents. They may be thought of as electronic code attached to (or associated with) a document which a) verifies the identity of the signer of the document and b) verifies that the document as signed by the signer has not been changed since the signing took place.
One common example of electronic signatures, commonly known as a digital signature, relies on public-key cryptography and hash functions to provide this verification. It will be appreciated that used herein the term “electronic signature” also refers to any signature process including symmetric and asymmetric signatures, whereas the term “digital signature” typically refers to an asymmetric signature.
FIG. 1 shows an example of a signing process that is utilised for the application of such electronic signatures.
The document to be signed is sent to a one-way hash function (Step 1) that computes a small hash that is (practically) unique to the document (Step 2). This hash has 2 key properties; firstly the hash is unique to the contents of the document and any change in the contents will cause a completely different hash to be generated (good hash functions result in a completely different number being generated for even a single bit change within the document), and secondly the hash is “practically” unique. In other words, the probability of two documents generating the same hash is extremely unlikely. This probability is a function of the size of the output hash and the “distribution” of the algorithm across the bits in the hash.
The hash itself is usually much smaller than the document itself. This is to allow public key encryption of it to be as fast as possible (given the processing power of some terminals and smart cards it is not currently practical to asymmetrically encrypt large documents (e.g. 1 MB of data). For a given hash algorithm, the hash output is the same size regardless of the size of the original document.
Next, the hash is sent to a signing function (Step 3). This is effectively an asymmetric encryption routine that uses the signer's private key to encrypt the hash. It should be noted that for non-repudiation, there are certain requirements for the management of the private key.
The document and the signature (which may be embedded in the document or linked to it in some fashion) are then sent to the recipient or stored (Step 4).
FIG. 2 shows an example of how a signature on a document may then be verified. The signed document package comprising the document and the document signature is presented for verification (Step 20). The hash values associated with both the document and the document signature are then computed. In the case of the document signature this computation uses the public key of the signer to decrypt the signature. This decryption produces the original document hash (Step 21). The two computed hash values are then compared (Step 22). If the hash values are found to be equivalent then the document is verified as having a valid signature (Step 23). If the values are not equivalent then the signature is found invalid (Step 24).
Although these techniques are satisfactory in that they allow a level of security to be applied to documents that are transferred between two or more persons or institutions, the protected documents are still vulnerable to attack by unscrupulous persons. It will be appreciated from the explanation of how the signature is applied to a document (FIG. 1) and how a document with a signature is then verified that all that is required for an unscrupulous person to impersonate the user's signature is to gain access to the private key. Furthermore, the signature is only tested against the keys themselves, there is no recourse back to ascertain the actual identity of the user who created or owns the signature. Typically, the private key is electronically stored locally by the user on a personal computer/laptop of the user or within a smart card belonging to that user. As such there is a possibility that a person of unscrupulous nature could gain access to such a key by gaining access to the personal computer or smart card and thereby effectively impersonate the user. There, therefore, exists a need for a modified technique for use in the protection of electronic documents.
Thus, the invention is directed towards providing improved convenience and security for management of personal documents and other items of data by citizens. It is a further object of the present invention to provide a method and apparatus for the improved control of electronic signature systems.